Basic Study on Temperature Dependence of Dry Rock Resistivity.

概要

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Resistivities of many types of dried rocks sampled from drilling core have been measured at temperature ranging from 372K to b73K under oxidizing and inert atmosphere. The resistivities and dielectric constants have been measured by placing the cylindrical rock piece between two electrodes. The results obtained are as follows, 1) The resistivities of many types of rock decrease with increasing temperature. 2) The resistivity of each rock shows hysteresis. One of the reason is that magnetite in the rock transform into hematite and has been confirmed by X-ray diffraction and magnetization measurements. 3) The temporary increase in rock resistivity has been caused by the formation of the intermediate product γ-hematite from magnetite before they finally transform into a-hematite when heated under oxidizing atmosphere. 4) Using the resistivity data of ten samples measured in an inert atmosphere, an empirical equation as a function of temperature is derived to predict the resistivities of rock. 5) Based on the resistivity data of taconite, magnetite and quartz, the mineral composition of the rock is calculated. If the resistivities of different minerals and their composition are known, rough esti-mates of dried rock resistivities will be possible.
日本地熱学会の論文